CFR 14-25.307-2014 Aeronautics and space. Part25:Airworthiness standards: transport category airplanes. SubpartC:Structure. Section25.307:Proof of structure.
(a) Compliance with the strength and deformation requirements of this subpart must be shown for each critical loading condition. Structural analysis may be used only if the structure conforms to that for which experience has shown this method to be reliable. In other cases, substantiating tests must be made to load levels that are sufficient to verify structural behavior up to loads specified in § 25.305.
CFR 14-25.307-2014 history
2014CFR 14-25.307-2014 Aeronautics and space. Part25:Airworthiness standards: transport category airplanes. SubpartC:Structure. Section25.307:Proof of structure.